The invention relates to a novel preparation of 3-fluoroquinolines of formula (I) in which R1, R2, R3 and R4 represent: a) a fluorine; b) an alkyl optionally substituted with one to three fluorines, with OR5 in which R5 is an alkyl, a hydrogen or a hydroxyl-protecting group, or with NR′R″ in which R′ and R″ represent an alkyl, a hydrogen or an amino-protecting group; c) OR6 in which R6 represents a hydrogen, a phenol-protecting group or an alkyl, optionally substituted with a fluorine, with OR5 or with NR′R″ as defined above; d) NR′1R″1 in which R′1 and R″1 have the values of R′ et R″ or represent an alkyl substituted with a fluorine, with OR5 or NR′R″ as defined above; e) CO2Ra, in which Ra represents hydrogen, alkyl or a carboxyl-protecting group, and also novel intermediate compounds. The quinolines of formula (I) are intermediates useful in the preparation of compounds having antibacterial activity, described in particular in applications WO 02/40474 or WO 02/72572.